JP2017026608A - Microchip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microchip that allows easy and ensured optical detection when a micro fluid is heated.SOLUTION: A microchip 1 according to the present invention includes a micro flow path 11 in a base plate 2. The micro flow path 11 has an optical detection part (fluorescence detection part 12) in the middle. The optical detection part has a first inner wall 12a and a second inner wall 12b, which are opposed to each other in a light travelling direction and are connected together with third inner walls 12c to 12f. The wettability of the first inner wall 12a and the second inner wall 12b to the micro fluid is set higher than the wettability of the third inner walls 12c to 12f to the micro fluid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microchip in which a microchannel is provided in a substrate.

  Conventionally, various microchips in which a microchannel is provided in a substrate have been proposed. This type of microchip is used for analysis of biological materials such as DNA and enzymes, and analysis of inorganic ions.

  For example, Patent Document 1 below discloses an example of the microchip. In the microchip described in Patent Document 1, bubble nucleus introducing means is formed on the entire inner peripheral surface of the microchannel at a predetermined position in the longitudinal direction of the microchannel. Specifically, a configuration in which a plurality of independent recesses are provided inside the bubble nucleus introducing means is disclosed.

Japanese Patent No. 4637610

  In the microchip described in Patent Document 1, bubbles are generated from a gas dissolved in a microfluid by a bubble nucleus introducing means, and the bubbles are removed. For this purpose, a plurality of independent recesses are provided on the inner wall. However, it has been difficult to completely collect the generated bubbles by such a method. In particular, when an operation including a heating step is performed like PCR, many bubbles derived from dissolved gas are generated by heating the microfluid. Therefore, when components such as DNA in a microfluid are detected by an optical detection method, the detection accuracy may be lowered or the detection itself may be difficult.

  An object of the present invention is to provide a microchip that enables optical detection easily and reliably even when the microfluid is heated.

  According to the present invention, there is provided a microchip in which a microchannel is provided in a substrate, and a component in a heated microfluid is optically detected in the middle of the microchannel in the substrate. An optical detection unit is provided, and the optical detection unit includes first and second inner walls facing each other in a direction in which light for detection travels, the first inner wall, and the first A third inner wall connecting the two inner walls, and the wettability of the first and second inner walls to the microfluid is higher than the wettability of the third inner wall to the microfluid. A microchip is provided.

  In a specific aspect of the microchip according to the present invention, the substrate has first and second main surfaces facing each other, and the first and second inner walls are the first and second main surfaces. Parallel to the surface. In this case, the optical detection part which has the 1st and 2nd main surface can be easily provided by the laminated body of a some plate-shaped member.

  In another specific aspect of the microchip according to the present invention, the substrate is a laminate formed by laminating a plurality of plate-like members. In this case, the microchip can be provided easily and inexpensively by stacking a plurality of plate-like members.

  In still another specific aspect of the microchip according to the present invention, the first and second inner walls are made of a material having higher wettability with respect to the microfluid than the third inner wall.

  In the microchip according to the present invention, the first and second inner walls may be surface-treated so as to enhance wettability to the microfluid.

  In the microchip according to the present invention, the third inner wall may be surface-treated so as to reduce wettability to the microfluid.

  In another specific aspect of the microchip according to the present invention, the optical detection unit is a detection unit for fluorescence analysis.

  In another specific aspect of the microchip according to the present invention, the component in the microfluid is a biological material.

  According to the microchip of the present invention, in the optical detection unit, the wettability of the first and second inner walls with respect to the microfluid is relatively high, so that the dissolved gas is used in the heated microfluid. Even if bubbles are generated, the bubbles adhere to the third inner wall side having relatively low wettability. Accordingly, bubbles are unlikely to adhere to the first and second inner walls, so that the components in the microfluid can be reliably detected by the optical detection unit.

(a) And (b) is the top view and front sectional drawing of the microchip which concern on one Embodiment of this invention. It is a partial notch expansion front sectional view which expands and shows the optical detection part in the microchip concerning one embodiment of the present invention. It is a schematic plan view for demonstrating the bubble adhesion state in the microchip of one Embodiment of this invention. It is a partial notch front sectional drawing for demonstrating the state of the 1st, 2nd and 3rd inner wall of the optical detection part in the microchip which concerns on other embodiment of this invention.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  1A and 1B are a plan view and a front sectional view of a microchip according to an embodiment of the present invention. 2 is a partially cutaway enlarged front cross-sectional view showing an optical detection unit in the microchip according to an embodiment of the present invention, and FIG. 3 is a view for explaining a state of bubble adhesion in the microchip. FIG.

  As shown in FIGS. 1A and 1B, the microchip 1 has a substrate 2. The board | substrate 2 consists of a laminated body formed by laminating | stacking several plate-shaped members 3-7. But the board | substrate 2 may be comprised with plate-shaped materials other than a laminated body.

  The substrate 2 has a first main surface 2a and a second main surface 2b facing each other. A micro flow path 11 is provided in the substrate 2.

  The micro flow path is a fine flow path that causes a so-called micro effect when liquid is transported. In such a microchannel, the liquid is strongly influenced by the surface tension and the capillary phenomenon, and behaves differently from the liquid flowing in a normal large-sized channel. The cross-sectional shape of such a microchannel is set to 5 mm or less, preferably 500 μm or less, more preferably 200 μm or less in terms of the dimension of the smaller side in the cross-section. When the cross section of the microchannel is circular, the diameter of the microchannel is set to 5 mm or less, preferably 500 μm or less, more preferably 200 μm or less.

  One end of the microchannel 11 is connected to an introduction port 11a for introducing a microfluid. A fluorescence detection unit 12 as an optical detection unit is provided in the middle of the microchannel 11. The fluorescence detection unit 12 passes through the plate-like members 4 to 6. That is, the micro flow path 11 is constituted by a slot provided in the plate-like member 5, and in the fluorescence detection unit 12, the plate-like members 4 and 6 are provided with through holes. The fluorescence detection unit 12 is provided in the substrate 2 by overlapping the through holes.

  The fluorescence detection unit 12 includes a first inner wall 12a, a second inner wall 12b, and a plurality of third inner walls 12c to 12f connecting the first inner wall 12a and the second inner wall 12b. The third inner wall may be acute or obtuse with respect to the first inner wall, and is preferably perpendicular to the first inner wall. The first inner wall 12a and the second inner wall 12b are arranged in parallel with the first main surface 2a and the second main surface 2b. The first inner wall and the second inner wall are flat surfaces, and preferably have a height of 50 μm or more and 2 mm or less, and more preferably 100 μm or more and 1 mm or less. Therefore, in the laminated body of the plurality of plate-like members 3 to 7, the fluorescence detection unit 12 having the first and second inner walls 12a and 12b can be easily formed, and the cost can be reduced.

  The shape of such a fluorescence detection unit may be a rectangular parallelepiped, a circle, an ellipse, or an asymmetric shape. The volume of the fluorescence detection unit is preferably 0.1 μl or more and 100 μl or less, more preferably 1 μl or more and 50 μl or less, and further preferably 4 μl or more and 25 μl or less.

  By the way, in the fluorescence detection part 12, the component in the conveyed microfluid is detected by fluorescence analysis. Therefore, it is desirable that the materials constituting the first inner wall and the second inner wall transmit light having a wavelength of 400 nm or more and 700 nm or less. In this case, in this embodiment, DNA amplified by PCR is detected. Therefore, in the fluorescence detection unit 12, the transported microfluid is heated. This heating can be achieved by providing a heating means so as to heat the microfluid in the fluorescence detection unit 12. Alternatively, a heating unit may be provided in a part of the microchannel 11 before reaching the fluorescence detection unit 12. The heating means is not particularly limited, and an appropriate heater or the like can be used. Heating may be performed only by the optical detection unit or may be performed by the entire microchip.

  Moreover, when the material which comprises a 1st inner wall and a 2nd inner wall has water vapor permeability, the outermost part of a 1st inner wall and a 2nd inner wall is covered with cycloolefin resin with low water vapor permeability. Also good.

  Further, a waste liquid section 13 is provided on the downstream side of the microchannel 11. The waste liquid part 13 is configured to store or discharge the microfluid after analysis.

  In the microchip 1, the fluorescence detection unit 12 performs the irradiation as fluorescence from the first main surface 2a side to the second main surface 2b side. That is, the first inner wall 12a and the second inner wall 12b are provided to face each other in the direction in which the fluorescence proceeds. More specifically, the 1st inner wall 12a and the 2nd inner wall 12b are extended in the direction orthogonal to the advancing direction of fluorescence.

  The feature of this embodiment is that the wettability of the first inner wall 12a and the second inner wall 12b to the microfluid being conveyed is higher than the wettability of the third inner walls 12c to 12f to the microfluid. There is to be.

  Note that the wettability of the first inner wall 12a and the second inner wall 12b with respect to the microfluid and the wettability of the third inner walls 12c to 12f with respect to the microfluid are determined by the contact angle with respect to the microfluid to be conveyed. Good. That is, the contact angle of the first inner wall 12a and the second inner wall 12b with respect to the microfluid to be conveyed should be smaller than the contact angle with respect to the microfluidic of the third inner walls 12c to 12f. The smaller the contact angle, the higher the wettability. The method described in JIS R3257 is used for measuring the contact angle.

  When the microfluid is heated, bubbles due to dissolved gas such as dissolved air are easily generated. If the bubbles are dispersed in a wide range in the fluorescence detection unit 12, it is difficult to detect the component to be detected by fluorescence analysis, and the sensitivity may be greatly reduced. In contrast, in the present embodiment, since the wettability of the first inner wall 12a and the second inner wall 12b with respect to the microfluid is relatively high, the generated bubbles are the third inner wall with relatively low wettability. It will adhere to the 12c-12f side. That is, as shown in FIG. 3, even if a plurality of bubbles C are generated, the bubbles C are unlikely to adhere to the first inner wall 12a and the second inner wall 12b side, which have relatively high wettability with respect to the microfluid. It will adhere on the plurality of third inner walls 12c to 12f. Therefore, in the large region including the center of the first inner wall 12a and the second inner wall 12b, the bubbles C are not present in the direction of fluorescence. Therefore, the components present in the fluorescence detection unit 12 can be reliably detected by fluorescence analysis.

  In the present embodiment, bubbles are preferentially generated near the third inner walls 12c to 12f and adhere to the third inner walls 12c to 12f. This is considered to be due to the fact that the lower the wettability, the easier the bubbles are generated on the surfaces of the third inner walls 12c to 12f with lower wettability and the adhesion to the surface.

  In the present embodiment, surface treatment such as plasma or corona treatment is performed on the surfaces of the first inner wall 12a and the second inner wall 12b. Accordingly, the wettability of the first inner wall 12a and the second inner wall 12b with respect to the microfluid is relatively increased.

  Conversely, the wettability may be lowered on the third inner walls 12c to 12f by surface treatment such as roughening.

  In addition, as shown in FIG. 4, surface treatment may be performed by providing coating layers 21 and 22 that can improve wettability to the microfluid on the first inner wall 12a and the second inner wall 12b. Alternatively, as shown by the alternate long and short dash line in FIG. 4, the third inner walls 12c and 12e may be coated with a material that relatively reduces wettability with respect to the microfluid and subjected to surface treatment for providing the coating layers 23 and 24. Good. Or you may comprise the material which comprises the 1st inner wall 12a and the 2nd inner wall 12b with the material whose wettability with respect to microfluid is higher than the material which comprises the 3rd inner walls 12c-12f.

  Further, the plate-like members 3 and 7 are made of a material having relatively high wettability and the surfaces of the plate-like members 4 to 6 are relatively low wettability. The material may be selected.

  Preferably, the first and second inner walls 12a and 12b have higher smoothness than the third inner walls 12c to 12f. Thereby, the wettability can be easily increased in the first and second inner walls 12a and 12b.

  The difference in contact angle between the first and second inner walls and the third inner wall is preferably 20 ° or more, more preferably 30 ° or more.

  The material of the said plate-shaped members 3-7 is not specifically limited. For example, an inorganic compound such as synthetic resin or synthetic rubber may be used, or an inorganic compound such as Si, glass, or ceramics may be used. Examples of the synthetic resin include acrylate resins such as polyethylene terephthalate and polymethyl methacrylate, polyolefins such as polycarbonate, polypropylene, and cycloolefin, and polystyrene. In addition, examples of the synthetic rubber include silicone resin rubber and SEBS. In addition, examples of the silicon resin include polydimethylsiloxane.

  In the above embodiment, the fluorescence detection unit 12 is provided as the optical detection unit, but an optical detection unit using light other than fluorescence may be used. In addition, the component to be measured in the microchip according to the present invention is not limited to DNA, but may be other biological materials such as extracellular materials. Moreover, the component in blood etc. may be sufficient. Furthermore, the microchip according to the present invention can also be used for analyzing trace ions such as inorganic ions.

  The liquid constituting the microfluid is not particularly limited, and may be various buffer solutions, aqueous solutions, biological extract liquid components, and the like.

  In the microchip 1, a micropump or the like for conveying a microfluid may be connected to the microchannel 11 as indicated by a dashed line A in FIG.

  Hereinafter, the present invention will be described in more detail by giving examples and comparative examples. In addition, this invention is not limited to a following example.

(Examples 1-6)
A microchip provided with a microchannel and an optical detection unit was prepared. However, in Examples 1 to 6, the first and second inner walls of the optical detection unit were formed of the resin shown in Table 1 below, and the third inner wall was formed of the resin shown in Table 1 below. . In Table 1, the contact angle with respect to the water of the 1st and 2nd inner wall and the contact angle with respect to the water of the 3rd inner wall are shown collectively.

(Comparative example)
As a comparative example, as shown in Table 1 below, except that the first and second inner walls are made of plasma-treated acrylic resin, and the third inner wall is made of plasma-treated cycloolefin resin, Microchips were obtained in the same manner as in Examples 1-6. In the comparative example, the contact angle of the first and second inner walls with respect to water was 10 ° as shown in Table 1, and the contact angle of the third inner wall with respect to water was also 10 °.

  The details of the resins constituting the first and second inner walls and the third inner wall used in Examples 1 to 6 and the comparative example are as follows.

  Example 1: The first and second inner walls were formed of acrylic resin (trade name: Acrylite L, manufactured by Mitsubishi Rayon Co., Ltd.). The third inner wall was formed of a cycloolefin resin (manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR1420R, having a cycloolefin structure).

  Example 2: The first and second inner walls were formed of plasma-treated acrylic resin (trade name: Acrylite L, manufactured by Mitsubishi Rayon Co., Ltd.). The plasma treatment was performed using a small plasma apparatus (Yamato Scientific Co., Ltd .: PM100). The condition was that oxygen was allowed to flow into the plasma gas phase at a flow rate of 100 ml / min for 10 minutes. The third inner wall was the same as the acrylic resin used in Example 1.

  Example 3 The first and second inner walls were the same as the first and second inner walls of Example 1. The third inner wall was subjected to fluorine coating (trade name: HIREC450, manufactured by NTTAT) on the surface of an acrylic resin (trade name: Acrylite L, manufactured by Mitsubishi Rayon Co., Ltd.).

  Example 4: The first and second inner walls were formed of the same acrylic resin as in Example 1. The third inner wall was formed of polydimethylsiloxane (manufactured by Toray Dow Corning, trade name: SILPOT 184).

  Example 5: The first and second inner walls were formed from plasma-treated polydimethylsiloxane. As polydimethylsiloxane, the same one as that used in the third inner wall of Example 4 was used, and hydrophilic treatment was performed by oxygen plasma. The third inner wall was formed of the same material as the third inner wall of Example 4.

  Example 6 For the first and second inner walls, the cycloolefin resin used in Example 1 to form the third inner wall was used. For the third inner wall, the fluorinated acrylic resin used in Example 3 to form the third inner wall was used.

  Comparative Example: The first and second inner walls were formed from the plasma-treated acrylic resin used in Example 2 to form the first and second inner walls. As the third inner wall, a cycloolefin resin manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR1420R, which has been subjected to a hydrophilic treatment with plasma, was used.

  The evaluation results of Examples 1 to 6 and Comparative Example are also shown in Table 1.

(Evaluation of Examples 1 to 6 and Comparative Example)
In each of the microchips of Examples 1 to 6 and the comparative example, a PCR reaction solution (TaKaRa Taq ^™ HS Fast Detect (manufactured by Takara Bio Inc.) was sent to the microchannel so as to fill the optical detection unit. The planar shape is rectangular, and has a dimension of 3 mm × 5 mm and a depth of 0.8 mm, so that the dimensions of the first inner wall, the second inner wall, and the third inner wall are as follows: The width is 3 mm and the height is 0.8 mm.

  The optical detection unit was viewed in plan with the optical detection unit filled with microfluidic. At this time, whether or not bubbles were generated was observed in a plan view. The evaluation results are shown in Table 1 above. The meanings of the evaluation symbols are as follows.

  A: Bubbles adhered to the third inner wall, but no bubbles adhered to the first and second inner walls.

  A: Most bubbles were attached to the third inner wall, and some bubbles were attached to the first and second inner walls.

  X: Many bubbles adhered to both the first and second inner walls and the third inner wall.

DESCRIPTION OF SYMBOLS 1 ... Microchip 2 ... Board | substrate 2a ... 1st main surface 2b ... 2nd main surface 3-7 ... Plate-shaped member 11 ... Micro flow path 11a ... Inlet 12 ... Fluorescence detection part 12a ... 1st inner wall 12b ... 2nd inner wall 12c-12f ... 3rd inner wall 13 ... Waste liquid part 21-24 ... Coating layer

Claims (8)

A microchip in which a microchannel is provided in a substrate,
An optical detector for optically detecting a component in the heated microfluid is provided in the middle of the microchannel in the substrate,
A third inner wall connecting the first and second inner walls, and the first inner wall and the second inner wall, facing each other in the direction in which the detection light travels. And
The microchip, wherein the wettability of the first and second inner walls with respect to the microfluid is higher than the wettability of the third inner wall with respect to the microfluid.   2. The micro of claim 1, wherein the substrate has first and second main surfaces facing each other, and the first and second inner walls are parallel to the first and second main surfaces. Chip.   The microchip according to claim 1 or 2, wherein the substrate is a laminate formed by laminating a plurality of plate-like members.   The microchip according to claim 1, wherein the first and second inner walls are made of a material having higher wettability to the microfluid than the third inner wall.   The microchip according to claim 1, wherein the first and second inner walls are surface-treated so as to enhance wettability with respect to the microfluid.   The microchip according to claim 1, wherein the third inner wall is surface-treated so as to reduce wettability with respect to the microfluid.   The microchip according to claim 1, wherein the optical detection unit is a fluorescence analysis detection unit.   The microchip according to claim 1, wherein a component in the microfluid is a biological material.

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